Unable to boot .img file

[Francesco Turco]

Hello,

I'm trying to boot a custom Linux system embedded into an .img file with 
grub2 under qemu, but I get the following error message:

Starting SeaBIOS (version 0.5.1-20100120_010601-rothera)
Booting from Hard Disk...
error: no such device 2efdc0e5-622a-4f80-ba01-41eaaf157b80.
grub rescue>

This is grub.cfg:

set timeout=10
set default=0

menuentry "Linux" {
        set root=(hd0,0)
        linux /boot/bzImage
}

This is what I did:

dd if=/dev/zero of=sysroot.img bs=1M count=512
losetup /dev/loop0 sysroot.img
fdisk /dev/loop0
losetup -o 32256 /dev/loop1 sysroot.img
mke2fs -t ext4 /dev/loop1
mount /dev/loop1 /mnt
(copied system files into /mnt)
grub-install --root-directory=/mnt /dev/loop0
umount /dev/loop1
losetup -d /dev/loop1
losetup -d /dev/loop0
qemu-system-x86_64 -hda sysroot.img

Where's the problem?

Thanks.